This tutorial explains data modulation in computer networks. Learn what data modulation is and how it works in computer networks.
Data modulation is a process that converts analog signals into digital signals and digital signals into analog signals. Computers store and process data in digital format. Data modulation allows computers to store and process analog signals.
Let’s take a simple example. When you record and play an audio clip, the following happens.
You use a microphone to record the audio clip. The microphone sends your voice to the computer. Since the human voice consists of analog signals, the computer converts the received voice into digital signals before processing and storing them onto the hard disk.
When the recorded clip is played, the computer reads digital signals from the hard disk and converts them into analog signals before sending them to the speaker.
The following image shows this process.
Modulators and demodulators are devices or chips or components that convert analog signals into digital signals and digital signals into analog signals, respectively.
Data modulation is not only used within the computer, but it is also used outside the computer. It allows computers to send digital signals on a media that can only carry analog signals. It converts signals in such a way that they become suitable for transport on a communication path that is not designed to carry such signals.
For example, telephone lines are designed to carry analog signals. Through data modulation, the same telephone lines can also be used to provide the Internet facility. To provide the Internet facility through telephone lines, a device known as the modem is used. A modem can act as both a modulator and a demodulator.
A modem connects a computer to the ISP network via a telephone line. It modulates digital signals into analog signals at the transmitting end, then demodulates analog signals into digital signals at the receiving end.
How does the data modulation work?
To convert digital signals into analog signals, a simple analog wave, known as the carrier wave, is combined into digital signals. A carrier wave does not contain any information or data. In simple words, it’s only a messenger that transfers information between two nodes.
An analog wave has four properties; amplitude, frequency, wavelength, and phase. From these, amplitude and frequency are used to blend digital signals. To load digital signals on the analog wave, the modulator modifies either amplitude or frequency in a pre-defined way.
To understand the properties of analog and digital signals in detail, you can check the tutorial.
After modification, the modulator loads the blended wave on the media. When the blended wave reaches its destination, the demodulator separates the data from the blended wave by using the same pre-defined way. After separation, the data is sent to its destination in the digital format and the carrier wave is discarded.
The following image shows an example of this process.
AM / FM Radio
A radio uses radio waves to receive the transmission from broadcasting stations. Radio waves can carry only analog signals. To transmit digital signals on radio waves, radio stations also use data modulation.
As mentioned above, digital signals can be mixed in the carrier wave either by modifying the amplitude or by modifying the frequency of the carrier wave. Based on the modified property, a radio station can be categorized into two types; AM radio station and FM radio station.
To broadcast the digital signals: -
An AM (Amplitude Modulation) radio station modifies the amplitude of the carrier wave.
An FM (Frequency Modulation) radio station modifies the frequency of the carrier wave.
Radio stations may also modify the phase (third property) of the carrier wave to broadcast multiple signals.
Digitizing analog signals
To convert analog signals into digital signals, an ADC (Analog to Digital Converter) is used. An ADC is an integrated electronic circuit. It takes input analog signals and converts them into digital (binary) signals.
An ADC converts the output data into a series of digital values by approximating the signals with fixed precision. In each cycle of the analog signal, an ADC measures all the falling and rising of signals and converts them into digital values.
To understand how an ADC converts analog signals into digital signals, think about a staircase and a ramp. A ramp is analog because it has an infinite number of heights. To construct a parallel staircase, a constructor uses sample heights of the ramp. The more samples the constructor takes, the more accurate the staircase will be.
The process of measuring the height and width of steps works similarly to the process of digitizing analog signals.
That's all for this tutorial. In this tutorial, we discussed data modulation and learned how it works in computer networks.